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Pig >> mail # user >> number of reducers


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Alex Rovner 2012-06-01, 15:49
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Re: number of reducers
What version of Pig are you running, and if it's not the trunk can you try
with the trunk?

There have been a number of improvements to how we get total input size
when estimating reducers. Basically, the input size is now requested from
the LoadFunc, which has more info about statistics.

See
https://issues.apache.org/jira/browse/PIG-2573
https://issues.apache.org/jira/browse/PIG-2693

On Fri, Jun 1, 2012 at 8:49 AM, Alex Rovner <[EMAIL PROTECTED]> wrote:

> Hello,
>
> We have wrote a HiveLoader that loads data from a hive warehouse
> (HCatalogue had roadblocks at the time and we decided against using it)
>
> We have one minor issue that would be great to solve: Currently pig cannot
> estimate correctly how many reducers to use when loading data from a hive
> warehouse.
>
> We have looked through the code and traced the problem to the following:
>
> Pig is using the location returned from "relativeToAbsolutePath" to figure
> out how many reducers it needs. In the case of loading from Hive, we do not
> know the paths that we need to load up until the setPartition() call is
> made. We can of course set the root of the table as the path in the
> "relativeToAbsolutePath" call but that would make pig over-estimate the
> number of reducers needed since we wont take into account the partition
> filtering that is taking place.
>
> Are there any workarounds for this issue?
> From my understanding, it would be sufficient if the relativeToAbsolutePath
> call was called after the setLocation and setPartition calls.
>
> Any input would be appreciated.
>
> Thanks
> Alex
>

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Alex Rovner 2012-06-01, 19:29
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Ashutosh Chauhan 2012-06-01, 18:02
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Alex Rovner 2012-06-01, 19:33
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Alan Gates 2012-06-03, 03:00